TNF and rheumatoid arthritis: To mimic the chronic inflammatory environment of RA, our osteochondral tissue model was treated for a prolonged period of 21 days repetitively (every 3 days) using a cocktail of three major RA-related cytokines, namely TNFα (10 ng/mL), IL-6 (30 ng/mL) and MIF (10 ng/mL) at pathophysiological, non-cytotoxic concentrations (Figure 7A–C).